A decade box is used when you need to introduce a variable resistance into a circuit in order to check the value of another resistor. In this case the value you are checking is the resistance value supplied by your resistance and continuity meter or multi-meter.

The decade resistor box contains a variable set of resistors, some of them in kilo ohms and some of them in mega ohms, which can be dialled in through interface buttons on the unit’s housing. The selected resistance value is then used to check that your meter readings are actually a true reflection of insulation or continuity in an electrical circuit. The resistors available for use in the box increase by multiples of ten which is why it is called a decade box.

Put the leads of the meter being checked into your Extech 380400 Resistance Decade Box, or similar decade resistor box, and dial in a resistance value. You should pick up exactly the same resistance value on your insulation tester or multi-meter. If you don’t, it needs attention from our Calibration Department.

We stock decade boxes by leading manufacturers, including the TEK903 and TEK 905 by Martindale.